1. Field of the Invention
The present invention relates to an improvement in an intake system.
2. Description of Background Art
A conventional intake system is known wherein a filter is pressed against an inner wall portion of a cleaner case by a filter holder so as to fix the filter to the cleaner case. See, for example, Japanese Patent Laid-open No. 2003-56420. In addition, the present inventor has provided a conventional intake system in which a base for supporting an air cleaner element is attached to a front surface of an air cleaner case by small screws. See, for example, Japanese Patent Laid-open No. 2003-56420.
As illustrated in FIG. 2(B) of Japanese Patent Laid-open No. 2003-56420, a cleaner case constitutes an air cleaner main body and is provided with an opening portion. An annular joint portion is provided for connecting an air feed tube by a fitting that projects on the periphery of the opening portion, one end portion of a filter abuts on an inner wall portion on the inside of the joint portion and is fixed by pressing it with a filter holder.
As illustrated in FIG. 3 of Japanese Utility Model Publication No. Hei 1-10319, a base is mounted to a front opening portion of an air cleaner case by small screws. An air cleaner element is mounted to the base by a mount bolt. A connecting tube connecting portion for connecting a connecting tube is provided at a front portion of the base portion 36
In Japanese Patent Laid-open No. 2003-56420, there is adopted a structure in which the surface of one end portion of the filter is fixed by pressing it against an inner wall portion of the cleaner case, so that when the width in the radial direction of the surface of the one end portion of the filter is enlarged, the cleaner case becomes larger in size, and the passage that is in communication from inside of the filter into the air feed tube is narrowed. Thus, the air feed quantity is reduced, and intake efficiency is lowered.
On the other hand, in Japanese Utility Model Publication No. Hei 1-10319, the mounting portion wherein the base is mounted to the air cleaner case by small screws is located on the outside in the radial direction of the air cleaner element, so that the front opening portion of the air cleaner case must be made larger than the outer shape of the air cleaner element by the mount portion, leading to an enlargement of the size of the air cleaner case. Or, in the case where the front opening portion of the air cleaner case is restricted to a predetermined size, the outer shape of the air cleaner element is smaller by the mount portion, so that the opening portion is also smaller, thus resulting in a reduction in the intake efficiency.